The adverb: in a way that relates to someone’s job, or because of the job. Doctors write that a person was occupationally exposed when their work put them in contact with a chemical, dust, or other risk. You will see it in medical and official English more than in chat. In speech people usually rebuild the sentence — “because of her job,” “at work” — rather than reach for occupationally. Same idea as occupational, just answering “how / in what way.”